Acceptance is not the same as permission. Acceptance is the beginning of an inquiry. It is the first step on a journey. Whereas permission, psychologically speaking, is allowing unhealthy behavior to continue.
Often people confuse the two. They think that if they accept something unpleasant about themselves, or another, that they are condoning bad behavior to continue. Instead, acceptance is living with things as they are, and then taking steps from there. Acceptance is living with oneself and others, warts and all, and then growing. Permission is suffering along with something you don't want, and feeling powerless to do something about it.
If I accept that I made a mistake or did something hurtful to someone that I love, it does not mean that I am okay to do it again, over and over. It does not mean that I permit myself to keep acting out. Rather, acceptance is the first step towards better understanding oneself and then working with what's there. It is a call to growth, and a chance to proceed with compassion.
For instance, if I accept that my partner has a difficult time with expressing their emotions, then I might have a chance to work with the situation and build from there. I might find a creative solution. Yet permission would mean that I'm ok with the lack of emotional expression and that I somehow just tolerate it. Where permission is allowing unpleasant things to continue, acceptance is the call to an imaginative solution. Knowing the difference between the two opens up all sorts of new possibilities.